Multirate digital filters are used in telecommunications, speech processing, image compression, antenna/radar systems, spectrum analysis, and in the wide myriad of applications and functions in the growing Internet of Things (IoT). “Multirate” literally means “multiple rates,” i.e., that there are multiple sampling rates being used in the system.
The basic building blocks of a multirate digital system are interpolation filters or interpolators, which increase the sampling rate of an input digital signal, and decimations filters or decimators, which decrease the sampling rate of an input digital signal.